ATTENUATION OF ALLERGEN-EVOKED NASAL RESPONSES BY LOCAL PRETREATMENT WITH EXOGENOUS NEUROPEPTIDE-Y IN ATOPIC PATIENTS

Background: Nasal obstruction and rhinorrhea present in allergic rhini tis are at least partly influenced by neuropeptides released from sens ory, parasympathetic, and sympathetic nerves. Neuropeptide Y (NPY) is co-localized with norepinephrine in sympathetic perivascular nerves. N PY is released with norepinephrine on sympathetic nerve stimulation an d produces long-lasting vasoconstriction of the nasal vascular bed. In addition to vasoconstriction, there is evidence to suggest that NPY m odulates the release of transmitters originating from parasympathetic and sensory nerves by acting on prejunctional receptors. Putative ther apeutic application of NPY in rhinitis has been recently suggested bec ause intranasal administration of exogenous NPY in human beings reduce s nasal airway resistance and vascular permeability without affecting submucosal gland secretion. Objective: The aim of this study was to de termine whether intranasal pretreatment with exogenous NPY could influ ence the functional responses to subsequent allergen challenge. Method s: A randomized double-blind, three-way, crossover, placebo-controlled study was performed in 13 patients with allergic rhinitis. Pretreatme nts with NPY (20 nmol), oxymetazoline hydrochloride (20 nmol), or sali ne solution (NaCl 0.9%) were administered in one nostril 5 minutes bef ore nasal challenge with grass pollen allergen (10,000 standardized qu ality units). The number of sneezes and the subjective evaluation of n asal itching, obstruction, and rhinorrhea were recorded. Nasal airway resistance was measured by anterior rhinomanometry, and nasal secretio ns were weighed. Mean arterial pressure and heart rate were recorded b y noninvasive methods. Results: The number of sneezes, nasal itching, and subjective rhinorrhea evoked by the allergen were similar after th e three pretreatments. Subjective and objective increases in nasal air way resistance and mucus production induced by the allergen were signi ficantly (p < 0.01) reduced after NPY pretreatment when compared with saline solution or oxymetazoline pretreatment. Mean arterial pressure and heart rate were not changed. Conclusions: Local pretreatment with exogenous NPY reduces nasal obstruction and mucus secretion evoked by allergen challenge in allergic patients without modification of local itching and number of sneezes.